When oxidizing agents, such as nitric acid HNO.sub.3 or hydrogen peroxide H.sub.2 O.sub.2, are added to solutions of hydrogen fluoride HF, silicon etching could be realized via an oxidation-etch mechanism. Such processes have been used to remove contaminants and crystal defects embedded near the surface region of the wafer, resulting in longer minority carrier lifetime and improved gate oxide reliability. However, the amount of silicon etched by this technique requires careful control and monitoring to minimize surface roughness degradation.
It is therefore desirable to provide for a gas phase equivalent chemistry for a silicon slight etch. In particular, it is desirable to provide for an etching process which yields minimal surface roughness which does not require extra energy excitation such as plasma or ultraviolet photon. Additionally, the desirable process still must yield advantageous characteristics such as longer minority carrier lifetime and improved gate oxide reliability.